1. Field of the Invention
The present invention relates to an image recording apparatus which allows an image to be recorded on a photosensitive material by an original image data signal by controlling light of three colors emitted from a light source, and a recording method in the image recording apparatus.
2. Description of the Related Art
A number of image recording apparatuses each having a digital exposure system mounted thereon has been nowadays developed. Generally, in the digital exposure system, an image is recorded on a recording medium in such a manner that a light beam outputted from a semiconductor laser carries image data and the light beam is deflected by high-speed rotation of a polygon mirror (main scanning), and further the light beam reflected by the polygon mirror is subjected to sub-scanning with a galvano mirror or the like, or the above main scanning is effected repeatedly while moving the recording medium (or moving the recording medium stepwise). Here, as the recording medium, a photosensitive drum electrified by corona discharge, a photosensitive material, or the like may be used. Further, in place of the semiconductor laser, other light emitter such as an LED may be used as a light source.
On the other hand, the resolution of an image to be recorded on a photosensitive material depends on the diameter of a spot to form an image (hereinafter referred to just "an image-forming spot") in either case of a semiconductor laser and an LED.
The diameter of the image-forming spot (hereinafter referred to an "image-forming spot diameter" or just a "spot diameter") is set by an image-formation optical system on an optical path and is basically set in accordance with the maximum resolution.
Here, when an image data signal whose resolution is different from that of an image recording apparatus is inputted, the resolution of the image data signal needs to coincide with that of the image recording apparatus by interpolating or sampling the inputted image data.
In this case, however, it is necessary to vary the input image data. For this reason, a lot of time is required for image processing and operating efficiency thereby deteriorates. Particularly, when an interpolating operation or the like is effected, the time for image recording remains unchanged irrespective of a small volume of image data.